It is well known to zoom-in (enlarge) an image or zoom-out (shrink) the image on a touch screen. For example, the Apple® iPHONE® mobile device permits a user to zoom-in an image by touching the screen with two fingers and sliding the two fingers away from each other, and to zoom-out an image by touching the screen with two fingers and sliding the two fingers toward each other. Other user controls are also known to request a zoom-in or a zoom-out of an image on a touch screen.
Mendis et al. (U.S. Pat. No. 8,468,469) discloses a first user selection at a first location on a graphically-displayed object of a touch screen, and zooming-in the object centered on a point that is along a line between a first and second location. The user indicates the first and second locations on the touch-screen by a press on the touch-screen at the first location and a release within a predetermined period of time at the second location. A direction of the zooming (i.e., zoom-in or zoom-out) is determined from the relative orientation of the first location to the second location. The magnitude of the zooming is based on the distance between the first and second locations and centered at the first location.
European Patent EP2256609 discloses a mobile device capable of implementing a touch-based zooming and control method with zoom-in and zoom-out actions depending on a move event. The mobile device executes a continuous zoom-out function around a selected point in response to the progress of a continuous move down event. The touch-screen has both a touch sensor unit used to execute an input function and a display unit used to execute an output function.
Gossweiler III et al. (U.S. Publication 20130016129) discloses a computing system recognizing a touch input gesture that includes a first touch input in a first zone of a touch screen that occurs simultaneous with a second touch input in a second zone of the touch screen. The first and second zones of the touch screen abut a periphery of the touch screen and have been established by the computing system as being zones for causing the computing system to react to touch input in a particular manner, in contrast to at least another zone of the touch screen for which the computing system does not react to touch input in the particular manner. The computing system modifies, in response to recognizing the touch input gesture, a display of the touch screen to react in the particular manner.
World Patent WO2008016387 discloses a three-dimensional touch pad input device with a zoom-in and zoom-out capability
Brooke U.S. Pat. No. 8,468,469) discloses a system and method for zooming an object through a spiral movement of a pointer. Monitoring the pointer movements determines whether a movement indicates a spiral movement. When a spiral movement is determined an object is zoomed. A clockwise spiral movement may zoom an object inwardly and a counterclockwise movement may zoom an object outwardly.